SUPPORTING INFORMATION
Combined Effect of Porosity and Surface Chemistry on the Electrochemical Reduction of Oxygen on Cellular Vitreous Carbon Foam Catalyst Jimmy Encalada,1 Keerthi Savaram2, Nikolina A. Travlou3, WanLu Li3, Qingdong Li2, Clara Delgado-Sánchez,4 Vanessa Fierro,4 Alain Celzard,4 Huixin He2 and Teresa J. Bandosz1, 3,** 1
Department of Chemistry, The City College of New York, 160 Convent Ave, New York, 10031,
USA: E-mail:
[email protected] 2
Department of Chemistry, Rutgers University, 73 Warren Street, Newark, NJ 07102, USA
3
Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New
York, NY 10016 4
Institut Jean Lamour, UMR Université de Lorraine – CNRS n°7198. ENSTIB, 27 rue Philippe
Séguin, BP 21042, 88051 Epinal cedex 9, France
1
250
Volume adsorbed STP [cm3/g]
3
Volume adsorbed STP [cm /g]
250
200
150
100 CM CM-N CM-S CM-H
50
0 0
0.2
0.4
0.6
0.8
1
Relative pressure [p/p ]
200
150
100 CM CMGO CMGO-H CMGO-S
50
0 0
0.2
0.4
0.6
0.8
1
Relative pressure [p/p0]
0
Figure S1. Nitrogen adsorption isotherms.
0.35
0.35 CM CM-N CM-S CM-H
CM CMGO CMGO-S CMGO-H
0.3
0.25
f(pKa) [mmol/g]
a
f(pK ) [mmol/g]
0.3
0.2 0.15 0.1 0.05
0.25 0.2 0.15 0.1 0.05
0 3
4
5
6
7
pK
8 a
9
10
11
0 3
4
5
6
7
8
9
10
11
pKa
Figure S2. pKa distributions
2
102 CM CM-N CM-S CM-H
100
98
Weight Loss [%]
Weight Loss [%]
100
96 94 92 90
CM CMGO CMGO-S CMGO-H
88
98
96
94
92
90
86 0
200
400
600
o
800
Temperature [ C]
1000
0
200
400
600
o
800
1000
Temperature [ C]
Figure S3. DTG curves in helium.
3
Figure S4. C1s, O1s, N1s and S2p core energy level spectra deconvolutions.
4
Table S1 . Peak position and numbers of groups calculated from potentiometric titration results (in parentheses; [mmol/g]). pKa 34 3.99 (0.161)
pKa 45
Sample
pH
GO
2.76
CM
8.83
4.76 (0.044)
CMGO
7.90
4.34 (0.095)
CM-N
8.56
CM-S
pKa 56 5.16 (0.209)
pKa 67 6.29 (0.283)
pKa 78 7.13 (0.504)
6.91 (0.059) 5.77 (0.075)
pKa 89 8.61 (0.514)
pKa 910 9.73 (0.626)
pKa 1011 10.61 (0.821)
All 3.118
9.66 (0.092)
0.195
6.97 (0.073)
7.99 (0.077)
9.77 (0.133)
0.453
4.47 (0.097)
6.02 (0.100)
7.39 (0.078)
9.29 (0.108)
0.383
9.90
4.77 (0.036)
6.48 (0.066)
9.31 (0.063)
0.165
CM-H
9.07
4.77 (0.036)
6.48 (0.066)
9.31 (0.063)
0.165
CMGOH
8.6
4.59 (0.067)
6.04 (0.048)
7.53 (0.061)
9.64 (0.147)
0.323
CMGOS
9.29
7.02 (0.069)
9.43 (0.074)
0.185
5.41 (0.042)
Table S2. ICP results for the CM sample Oxide Al2O3 BaO CaO Cr2O3 CuO Fe2O3 K2O MgO MnO2 Na2O NiO SiO2 TiO2 ZnO
[%] 0.25 0.31 19.91 0.02 0.10 0.01 50.98 26.05 0.34 0.20 0.01 1.16 0.04 0.61
element Al Ba Ca Cr Cu Fe K Mg Mn Na Ni Si Ti Zn
[ppm] 26 55 2756 3 16 1 8196 3044 41 28 2 105 5 95
5
Figure S5. Linear sweep voltammograms of CM carbons on modified glassy carbon RRDE in O2-saturated 0.10 M KOH at different rotation speeds and scan rate of 100 mV/s for the materials studied.
6
0 5 10
-5
Current (A)
0.0001 0.00015
CM CMGO CM-N CM-S CM-H CMGO-H CMGO-S
0.0002 0.00025 0.0003 0.00035 0.2
0.4
0.6
0.8
1
1.2
Potential (V) vs. RHE
Figure S6. Linear sweep voltammograms on the RRDE in O2 saturated 0.1 M KOH at 2000 rpm and scan rate of 5 mV s-1.
7
0.45 0.40
(A)
i-1 [A-1cm2]
0.35 0.30 0.25 CM CM-H CMGO CMGO-H CMGO-S CM-N CM-S
0.20 0.15 0.10
0.020 0.025 0.030 0.035 0.040 0.045 0.050
ω-1/2 [rad-1/2s-1]
Effective Diffusion Coefficient [cm2s-1]
5.50E-009 5.00E-009
CM CM-H CMGO CMGO-H CMGO-S CM-N CM-S
(B)
4.50E-009 4.00E-009 3.50E-009 3.00E-009 2.50E-009 2.00E-009 1.50E-009 0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
Potential vs RHE [V]
0.00018
CM CM-H CMGO CMGO-H CMGO-S CM-N CM-S
Kinetic rate constant [cm s-1]
(C) 0.00016
0.00014
0.00012
0.00010
0.00008
0.00006 0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
Potential vs RHE [V]
Figure S7. A) K-L plots; B) effective diffusion coefficient of O2 (D0); and C) kinetic rate constants k.
8
